Viewing posts from November, 2015

A Blue, Neptune-Size Exoplanet Around a Red Dwarf Star

A team of astronomers have used the LCOGT network to detect light scattered by tiny particles (called Rayleigh scattering), through the atmosphere of a Neptune-size transiting exoplanet. This suggests a blue sky on this world which is only 100 light years away from us. The result was published in the Astrophysical Journal on November 20 (and is available on ArXiV).

Transits occur when an exoplanet passes in front of its parent star, reducing the amount of light we receive from the star by a small fraction. When the orbit of an exoplanet is aligned just right for transits to occur, astronomers can measure the planet’s size at different wavelengths in order to generate a spectrum of its atmosphere. The spectrum then reveals the substances present in the planet’s atmosphere, and therefore its composition. This measurement is most often performed using infrared light, where the planet is brightest and most easily observed. During the last few years, researchers have been probing the atmospheres of several small exoplanets with large ground and space-based telescopes, but have found it challenging to determine their composition using this method. This is either because the planets have clouds (which obscure the atmosphere) or because the measurements were not sufficiently precise.
Image credit: NAOJ

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